JP2015050842A - Power storage system, power storage controller and power storage control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system, a power storage controller and a power storage control method capable of preventing overcurrent of charging current.SOLUTION: The power storage system includes: two or more battery units including one or two or more cells connected to each other in parallel each having a monitor for monitoring the state of charge; one or two or more chargers each of which supplies charging current to each battery unit; and one or two or more power storage controllers that control the value of charging current supplied to each battery unit. The power storage controller is configured to reduce the value of charging current according to the state of charge of each battery unit.

Description

  The present disclosure relates to a power storage system, a power storage control device, and a power storage control method. More specifically, the present invention relates to a power storage system, a power storage control device, and a power storage control method for charging a cell.

  Conventionally, a technique related to a power supply device in which a plurality of secondary batteries are connected in parallel has been proposed. For example, in Patent Document 1, in a power supply apparatus in which a plurality of series-connected battery blocks in which a plurality of chargeable / dischargeable secondary batteries are connected in series are connected in parallel, a constant current control circuit is provided in each of the series-connected battery blocks. Has been proposed. According to the power supply device described in Patent Literature 1, when the series-connected battery blocks are connected in parallel, the series-connected battery block having a low potential difference can be prevented from being damaged by the inrush current.

JP 2006-345660 A

  When a plurality of secondary batteries are connected in parallel and each secondary battery is actually charged, an overcurrent of the charging current may occur.

  The present disclosure provides a power storage system, a power storage control device, and a power storage control method that prevent an overcurrent of a charging current.

The power storage system according to the present disclosure includes one or more cells and two or more battery units connected to each other in parallel, each of which includes a monitoring device that monitors a charge state, and supplies a charging current to each battery unit. The battery charger, and one or more power storage control devices for controlling the charging current value supplied to each battery unit, the power storage control device according to the charge state of each battery unit. The value is decreased. Here, the “charged state” refers to the progress of charging (hereinafter the same).
The battery unit includes a shut-off device that cuts off the connection with the charger when the voltage reaches an upper limit voltage value, and the power storage control device has a specific voltage value in which the voltage of the battery unit is smaller than the upper limit voltage value. In this case, the charging current value may be decreased.
In that case, the power storage control device causes the charger to supply a constant current value until the battery unit having the specific voltage value is first detected, and the battery unit having the specific voltage value is first supplied. After the detection, the current value supplied to the charger may be adjusted so that the charging current value supplied to each battery unit is equal to or less than the constant current value.
Further, the power storage system may include two or more power storage control devices and share charging information between the two or more power storage control devices. In this case, the power storage system may include a communication line that connects the two or more power storage control devices to each other, and the two or more power storage control devices may transmit and receive the charging information to each other via the communication line. . The first power storage control device in the two or more power storage control devices acquires the charging information from the monitoring device corresponding to the first power storage control device, and the charging information is used as the two or more power storage control devices. You may transmit to the 2nd electrical storage control apparatus in. Here, “charging information” is information indicating a charging state (hereinafter the same).
Further, the power storage control device may adjust the charging current value according to the number of the battery units having a voltage equal to or higher than the specific voltage value. In that case, the power storage control device may perform the adjustment including reducing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases. Here, “the adjustment including reducing the charging current value” includes an aspect of the adjustment that the charging current value is reduced as the number of battery units having a voltage equal to or higher than the specific voltage value increases. If so, it means that other modes may be included in the adjustment depending on conditions (the same applies hereinafter).
The power storage control device may perform the adjustment including gradually decreasing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases. The “adjustment including gradually decreasing the charging current value” means that the charging current value is gradually decreased as the number of battery units having a voltage equal to or higher than a specific voltage value is increased. If included in the aspect, it means that other aspects may be included in the adjustment according to the conditions (hereinafter the same).
The power storage control device according to the present disclosure has a configuration in which a charging current value supplied to two or more battery units including one or two or more cells and connected in parallel to each other is reduced according to a charging state of each battery unit. is there.
The power storage control method according to the present disclosure reduces the charging current value supplied to the battery unit according to the state of charge of two or more battery units including one or more cells and connected in parallel to each other.

  According to the present disclosure, overcurrent of the charging current can be prevented.

It is a figure showing typically an example of composition of an electrical storage system of a 1st embodiment of this indication. 3 is a flowchart illustrating an operation example of the power storage system according to the first embodiment of the present disclosure. It is a figure which shows typically the structure of the electrical storage system of the modification of 1st Embodiment of this indication. It is a figure which shows typically the structural example of the electrical storage system of 2nd Embodiment of this indication. 14 is a flowchart illustrating an operation example of the power storage system according to the second embodiment of the present disclosure. It is a figure which shows typically the structure of the electrical storage system of the modification of 2nd Embodiment of this indication. It is a time chart which shows the operation example of the electrical storage system of 3rd Embodiment of this indication, A is a time chart corresponding to a 1st battery unit, B is a time chart corresponding to a 2nd battery unit. . It is a figure which shows typically the structural example of the electrical storage control part in the electrical storage system of 4th Embodiment of this indication. 14 is a flowchart illustrating an operation example of the power storage system according to the fourth embodiment of the present disclosure. It is a flowchart which shows the specific example of a part of process of the flowchart of FIG. It is a figure which shows typically the structure of the 1st modification of the electrical storage system of 4th Embodiment of this indication. It is a figure which shows typically the structure of the 2nd modification of the electrical storage system of 4th Embodiment of this indication. It is a figure which shows typically the structure of the 3rd modification of the electrical storage system of 4th Embodiment of this indication. It is a time chart which shows the operation example of the electrical storage system of 5th Embodiment of this indication, A is a time chart corresponding to a 1st battery unit, B is a time chart corresponding to a 2nd battery unit, C These are time charts corresponding to a 3rd battery unit. 16 is a flowchart illustrating an operation example of the power storage system according to the fifth embodiment of the present disclosure. It is a time chart which shows operation | movement of the electrical storage system of the modification of 5th Embodiment of this indication, A is a time chart corresponding to a 1st battery unit, B is a time chart corresponding to a 2nd battery unit. , C are time charts corresponding to the third battery unit. It is a time chart which shows operation | movement of the electrical storage system of the comparative example of 5th Embodiment of this indication, A is a time chart corresponding to a 1st battery unit, B is a time chart corresponding to a 2nd battery unit. , C are time charts corresponding to the third battery unit.

Hereinafter, preferred embodiments for carrying out the present disclosure will be described with reference to the drawings. A plurality of embodiments described below show examples of typical embodiments of the present disclosure, and the scope of the present disclosure is not interpreted narrowly. Moreover, in each embodiment, about the component corresponding to each other, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. The description will be made in the following order.

1. 1st Embodiment (example of the electrical storage system which reduces a charging current value according to the charge condition of each battery unit)
2. Modified example of first embodiment (an example of a power storage system including a plurality of chargers and a power storage control unit as an example of a power storage control device, and a battery unit including a plurality of cells)
3. Second embodiment (an example of a power storage system including a switch control unit as an example of a shut-off device)
4). Modified example of second embodiment (an example of a power storage system including a plurality of chargers and a power storage control unit)
5. Third embodiment (an example of a power storage system to which constant current charging is applied)
6). Fourth embodiment (an example of a power storage system sharing charging information)
7). First modification of the fourth embodiment (an example of a power storage system including a communication line)
8). Second modification of the fourth embodiment (an example of a power storage system in which the battery unit includes a plurality of cells)
9. Third modified example of the fourth embodiment (an example of a power storage system including a plurality of power storage units)
10. Fifth embodiment (an example of a power storage system that adjusts a charging current value according to the number of battery units having a voltage equal to or higher than a specific voltage value)
11. Modified example of the fifth embodiment (an example of a power storage system corresponding to the end of simultaneous charging)

<1. First Embodiment>
[System configuration example]
FIG. 1 is an overall view schematically showing a configuration example of a power storage system 100 of the present embodiment. As illustrated in FIG. 1, the power storage system 100 includes a plurality of battery units 110, a charger 102, and a power storage control unit 120 as an example of a power storage control device according to the present disclosure.

[Charger 102]
The charger 102 is connected to the battery unit 110 via the power line 104. The charger 102 is connected to a power source (not shown). The charger 102 charges the battery unit 110 based on the power supplied from the power source.

  The charger 102 may charge the battery unit 110 by supplying a charging current having a set charging current value to the battery unit 110. The mode of the charger 102 is not limited, and various types of chargers capable of adjusting the charging current value can be employed. For example, the charger 102 may be configured by an electronic device or the like that adjusts the current value of the charging current flowing from the power supply side to the battery unit 110 side. The electronic device may include an electronic circuit or the like. The electronic circuit may include a semiconductor element or the like. The semiconductor element may be a transistor or the like. The charging current value may be set, for example, by applying a signal to the electronic device such as applying a base current to the bipolar transistor or applying a gate voltage to the unipolar transistor. The power source may be, for example, a solar cell, a wind power generator, a power plant, or the like. Alternatively, the charger 102 itself may have a power generation function.

[Battery unit 110]
The battery units 110 are connected to each other in parallel via the power line 104. The number of battery units 110 is not limited to two as shown in FIG. 1, and may be appropriately selected according to the output to be generated.

  As shown in FIG. 1, the battery unit 110 includes a chargeable / dischargeable cell 111 and a monitoring unit 112 as an example of a monitoring device.

[Cell 111]
The cell 111 is connected to the charger 102 via the power line 104. The cell 111 is arranged in such a direction that the upstream side in the inflow direction of the charging current into the cell 111 is a positive electrode and the downstream side is a negative electrode. When the cell 111 is charged, the cell 111 stores the charging current supplied from the charger 102 as a charge. The cell 111 can supply the accumulated electric charge as a discharge current to the load during discharge. The kind of cell 111 is not limited, For example, a lithium ion secondary battery etc. can be employ | adopted suitably. By employing a lithium ion secondary battery, the energy density and output of the cell 111 can be increased, self-discharge of the cell 111 can be suppressed, or the life of the cell 111 can be improved.

[Monitoring unit 112]
The monitoring unit 112 is connected to the cell 111. The monitoring unit 112 monitors the state of charge of the battery unit 110. The monitoring of the charging state may be realized by electrically detecting a physical quantity indicating the charging state from the battery unit 110, calculating a parameter indicating the charging state based on the detection result of the physical quantity, or the like. For example, the monitoring unit 112 monitors the charge state by continuously detecting the voltage of the battery unit 110, that is, the total value of the voltages of the cells 111 included in the battery unit 110 (hereinafter referred to as cell voltage). Also good. FIG. 1 schematically shows how the cell voltage is detected by the monitoring unit 112, and the detection result of the cell voltage is reflected in the detection result of the voltage of the battery unit 110. In addition to the voltage of the battery unit 110, it is within the scope of the present disclosure if a value corresponding to the progress of charging of the battery unit 110, that is, the degree of progress is monitored. For example, the monitoring unit 112 may monitor the state of charge by continuously calculating the ratio of the remaining capacity to the full charge capacity of the battery unit 110.

  The monitoring unit 112 may monitor the deterioration state of the battery unit 110, that is, the degree of deterioration, in addition to the charging state. The monitoring of the deterioration state may be realized by electrically detecting a physical quantity indicating the deterioration state from the battery unit 110 or calculating a parameter indicating the deterioration state based on the detection result of the physical quantity. For example, the monitoring unit 112 may monitor the deterioration state by detecting the discharge voltage of the battery unit 110 or calculating the ratio of the full charge capacity after deterioration to the initial full charge capacity of the battery unit 110. Good.

  The monitoring unit 112 outputs the monitoring result to the power storage control unit 120. The monitoring unit 112 may be configured by an electronic device or the like. The electronic device may include an electronic circuit or the like. The electronic circuit may include an integrated circuit or the like.

[Power storage control unit 120]
The power storage control unit 120 controls the operation of the charger 102 to control the charging current value supplied from the charger 102 to each battery unit 110. The power storage control unit 120 sets the charging current value to the charger 102 to supply the charging current having the set charging current value.

  When the battery units 110 connected in parallel are actually charged, the charging current flowing through the battery units 110 may become an overcurrent due to variations in the charging state of the battery units 110. In order to prevent this type of overcurrent, the present embodiment controls the charging current value as follows.

  The power storage control unit 120 decreases the charging current value supplied to the battery unit 110 according to the charge state of each battery unit 110. The power storage control unit 120 may decrease the charging current value supplied to the battery unit 110 by decreasing the charging current value set in the charger 102. The power storage control unit 120 may acquire the state of charge from the monitoring unit 112.

  The power storage control unit 120 may be configured by an electronic device or the like. The electronic device may include an arithmetic processing device such as a CPU (Central Processing Unit) and an MPU (Micro-Processing Unit) and a storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ROM may store a program for realizing the function of the power storage control unit 120, that is, software or data. The arithmetic processing unit may realize the function of the power storage control unit 120 by executing a program stored in the ROM. The RAM may be used as a work area for the arithmetic processing unit. However, it is not limited to such a configuration.

[System operation example]
FIG. 2 is a flowchart illustrating an operation example of the power storage system 100 of the present embodiment. The operation example illustrated in FIG. 2 includes an embodiment of the power storage control method according to the present disclosure. However, the power storage control method according to the present disclosure may be embodied with a configuration other than the power storage system 100.

  For convenience of explanation, it is assumed that a charging current value is set in the charger 102 by the power storage control unit 120 in the initial state of FIG.

  Then, from the initial state, first, in step 11 (S11) of FIG. 2, charging of the battery unit 110 is started by supplying the charging current of the set charging current value to the battery unit 110 by the charger 102. .

  Next, in step 12 (S12), the monitoring unit 112 monitors the state of charge.

  Next, in step 13 (S13), the power storage control unit 120 determines whether or not the current charging state is a charging state in which the charging current value of the charger 102 should be decreased. If a positive determination result is obtained in step 13 (S13), the process proceeds to step 14 (S14). If a negative determination result is obtained, the process proceeds to step 15 (S15).

  Here, when it progresses to step 14 (S14), the electrical storage control part 120 reduces the charging current value of the charger 102. FIG. Thereafter, the process is terminated, or the process returns to step 12 (S12) as necessary. The termination of the process may include terminating the operation of the charger 102.

  On the other hand, when it progresses to step 15 (S15), a charging current value is maintained and it returns to step 12 (S12).

  As described above in detail, according to the power storage system 100 of this embodiment, the charge current value supplied from the charger 102 to each battery unit 110 by the power storage control unit 120 depends on the state of charge of each battery unit 110. Will be reduced. Thereby, the overcurrent of the charging current can be effectively prevented.

<2. Modification of First Embodiment>
FIG. 3 is an overall view schematically showing a configuration of a power storage system 100 according to a modification of the present embodiment. The power storage system 100 of the present modification is different from the power storage system 100 of FIG. 1 in the arrangement of the cells 111, the charger 102, and the power storage control unit 120.

  Specifically, as shown in FIG. 3, in the power storage system 100 of this modification, each battery unit 110 includes a plurality of cells 111. The number of cells of each battery unit 110 may be the same or different from each other.

  As shown in FIG. 3, the power storage system 100 according to the present modification includes a plurality of chargers 102 and power storage control units 120 corresponding to the respective battery units 110. In this modification, each charger 102 charges the corresponding battery unit 110. Moreover, in this modification, each power storage control unit 120 sets the charging set to the charger 102 corresponding to itself according to the charging state of the battery unit 110 corresponding to itself and the charging state of the other battery unit 110. Decrease the current value. Other configurations and operations are basically the same as those of the power storage system 100 of FIG.

  According to this modification, the same operational effects as the power storage system 100 of FIG. 1 can be obtained, and the charging current value can be quickly controlled for each battery unit 110. Furthermore, even if the battery unit 110 includes a plurality of cells 111 and thus the state of charge among the battery units 110 is likely to vary, overcurrent can be effectively prevented.

<3. Second Embodiment>
[System configuration example]
FIG. 4 is an overall view schematically showing a configuration example of the power storage system 100 of the present embodiment. As shown in FIG. 4, the power storage system 100 of the present embodiment is different from the power storage system 100 of FIG. 1 in that the battery unit 110 includes a switch control unit 113 and a switch 114 as an example of a shut-off device. Further, the power storage system 100 of the present embodiment is different from the power storage system 100 of FIG. 1 in that the power storage control unit 120 can also reduce the charging current value of the charger 102 at a timing that takes into account the operation of the switch 114. . Furthermore, in the power storage system 100 of the present embodiment, the power storage control unit 120 is connected to the monitoring unit 112 and the charger 102 via the signal line 105. Other configurations are basically the same as those of the power storage system 100 of FIG.

[Battery unit 110]
[Switch 114]
The switch 114 is disposed on the power line 104 at a position closer to the charger 102 than the cell 111. The switch 114 enters the selected operating state. The operating state includes an on state and an off state. The on state is a state in which the switch 114 closes the electric circuit between the charger 102 and the cell 111. The off state is a state in which the switch 114 opens the electric circuit between the charger 102 and the cell 111. In the ON state, charging of the cell 111 by the charger 102 or discharging from the cell 111 is allowed. In the off state, charging and discharging are impossible. The mode of the switch 114 is not limited. For example, the switch 114 may be configured by a semiconductor element or the like. The semiconductor element may be a transistor or the like. The transistor may be a field effect transistor or the like. By using a field effect transistor, power consumption can be suppressed.

[Switch control unit 113]
The switch control unit 113 is connected to the monitoring unit 112 and the switch 114. The switch control unit 113 selects an operation state of the switch 114. For example, the switch control unit 113 switches the switch 114 from the on state to the off state, or switches the off state to the on state by applying an electrical signal to the switch 114.

  When the voltage of the battery unit 110 reaches the upper limit voltage value, the switch control unit 113 functions as a disconnecting device and disconnects the connection between the battery unit 110 and the charger 102. Thereby, it is possible to prevent an overvoltage from being applied to the battery unit 110. The switch control unit 113 may detect that the voltage of the battery unit 110 has reached the upper limit voltage value based on the state of charge acquired from the monitoring unit 112. The switch control unit 113 may switch off the connection between the battery unit 110 and the charger 102 by switching the switch 114 from the on state to the off state.

  The electric signal applied from the switch control unit 113 to the switch 114 may be a base current of a bipolar transistor or the like, or a gate voltage of a unipolar transistor or the like. The unipolar transistor may be a field effect transistor as described above. The switch control unit 113 may be configured by an electronic device or the like. The electronic device may include an electronic circuit or the like. The electronic circuit may include an integrated circuit or the like. The switch control unit 113 may be configured integrally with the monitoring unit 112, for example, a configuration arranged in the same battery protection circuit, or may be configured separately from the monitoring unit 112. By integrating the switch control unit 113 and the monitoring unit 112, the number of parts can be reduced and the circuit can be made compact.

[Power storage control unit 120]
Depending on the variation in the state of charge of each battery unit 110, the timing of the end of charging of each battery unit 110 may differ. Specifically, a certain battery unit 110 may reach an upper limit voltage value earlier than other battery units 110 and may be disconnected from the charger 102 by the operation of the switch 114. In this case, the charging current of the charger 102 that has lost its place due to interruption flows into the other battery unit 110 being charged as a cross current. Thereby, the charging current of the battery unit 110 being charged may become an overcurrent. In order to prevent this type of overcurrent, the present embodiment controls the charging current value as follows.

  The power storage control unit 120 decreases the charging current value when the voltage of the battery unit 110 becomes a specific voltage value smaller than the upper limit voltage value. The power storage control unit 120 may detect that the battery unit 110 has reached a specific voltage value based on the state of charge acquired from the monitoring unit 112. The aspect of the specific voltage value is not limited. For example, a suitable value near the upper limit voltage value smaller than the upper limit voltage value may be set as the specific voltage value. The specific voltage value may be a voltage value that is regarded as immediately before the end of charging, that is, immediately before the switch 114 is switched to the OFF state from the relationship with the upper limit voltage value.

[System operation example]
FIG. 5 is a flowchart illustrating an operation example of the power storage system 100 of the present embodiment. The operation example illustrated in FIG. 5 includes an embodiment of the power storage control method according to the present disclosure.

  In the operation example of this embodiment, step 21 (S21) is executed as a specific example of the step instead of step 13 (S13) in FIG. 2, and step 22 (ST22) and step 23 (after step 14 (ST14)) are executed. It differs from the first embodiment in that S23) is executed.

  In step 21 (S21), the power storage control unit 120 determines whether or not the voltage of the battery unit 110 has reached a specific voltage value. When a positive determination result is obtained in step 21 (S21), the process proceeds to step 14 (S14), and when a negative determination result is obtained, the process proceeds to step 15 (S15).

  In step 22 (S22), the switch control unit 113 determines whether or not the voltage of the battery unit 110 has reached the upper limit voltage value. If a positive determination result is obtained in step 22 (S22), the process proceeds to step 23 (S23). If a negative determination result is obtained, step 22 (S22) is repeated.

  In step 23 (S23), the switch controller 113 switches the switch 114 from the on state to the off state, thereby disconnecting the battery unit 110 from the charger 102. Thereafter, the process is terminated, or the process returns to step 12 (S12) as necessary.

  According to the present embodiment, the same operational effects as the power storage system 100 of FIG. 1 can be obtained, and the charging current value of the charger 102 is reduced in advance before the occurrence of a cross current due to the interruption of the charger 102. Therefore, overcurrent can be avoided in advance.

<4. Modification of Second Embodiment>
FIG. 6 is an overall view schematically showing a configuration of a power storage system 100 according to a modification of the present embodiment. The power storage system 100 of this modification is different from the power storage system 100 of FIG. 4 in that a plurality of chargers 102 and power storage control units 120 are provided corresponding to the respective battery units 110. In this modification, each charger 102 charges the corresponding battery unit 110. Further, in this modification, each power storage control unit 120 sets the charger 102 corresponding to itself when any one of the battery unit 110 corresponding to itself and the other battery unit 110 reaches a specific voltage value. Decrease the charging current value. Other configurations and operations are basically the same as those of the power storage system 100 of FIG.

  According to this modification, the same operational effects as the power storage system 100 of FIG. 4 can be obtained, and the charging current value can be quickly controlled for each battery unit 110.

<5. Third Embodiment>
FIG. 7 is a time chart showing an operation example of the power storage system 100 of the present embodiment. FIG. 7 shows a time chart for two battery units 110. The horizontal axis in FIG. 7 indicates time (t). The vertical axis in FIG. 7 indicates the charging current values (I1, I2) flowing through each battery unit 110 and the voltages (V1, V2) of each battery unit 110. Hereinafter, the battery unit 110 corresponding to the time chart of FIG. 7A is defined as the first battery unit 110, and the battery unit 110 corresponding to the time chart of FIG. 7B is defined as the second battery unit 110.

  In the power storage system 100 of this embodiment, the control content of the power storage control unit 120 is added to the power storage system 100 of the second embodiment.

  Specifically, the power storage control unit 120 causes the charger 102 to supply a constant current value until the battery unit 110 having a specific voltage value is first detected. In the example of FIG. 7, the first battery unit 110 having a specific voltage value is the first battery unit 110 (FIG. 7A), and the first battery unit 110 has the specific voltage value (SV) until the first battery unit 110 reaches the specific voltage value (SV). A constant current value (Ic) is supplied to the first and second battery units 110.

  Then, after the battery unit 110 having a specific voltage value is first detected, the power storage control unit 120 adjusts the current value to be supplied to the charger 102 and the charging current value supplied to each battery unit 110. Is controlled below a certain current value. In the example of FIG. 7, after the time T1 when the first battery unit 110 reaches the specific voltage value, the charging current value of the charger 102 is decreased from the constant current value (Ic). Thereby, even after the first battery unit 110 reaches the upper limit voltage value (ULV) at time T2 and is disconnected from the charger 102, the charging current value (I2) of the second battery unit 110 is kept at a constant current value ( Ic) The following can be maintained:

  Here, the adjustment of the current value to be supplied to the charger 102 does not exclude the inclusion of aspects other than the decrease of the current value as long as the decrease of the current value is included as one aspect. Specifically, if the charge current value of the battery unit 110 can be controlled to a constant current value or less by adding the cross current from the other battery unit 110 side, adjustment including maintenance and / or increase of the current value is possible. Is also within the range of adjustment of the current value in the present disclosure. In other words, as long as no overcurrent occurs, for example, maintaining or increasing the current value of the charger 102 from the viewpoint of sufficiently securing the charging current supplied to the battery unit 110 is also within the scope of the present disclosure. It is. Ensuring a sufficient charging current value may lead to a reduction in the time required for charging. In the example of FIG. 7, when the second battery unit 110 reaches the specific voltage value (SV) at time T3, the charging current value of the charger 102 is maintained at the value decreased at time T1. Thereby, after the time T3, until the second battery unit 110 is disconnected from the charger 102, the charging current value (I2) of the second battery unit 110 is the value between the time T2 and the time T3. Maintained.

  According to the present embodiment, the same operational effects as the power storage system 100 of FIG. 4 or 6 can be obtained, and the occurrence of overcurrent when performing constant current charging can be prevented.

<6. Fourth Embodiment>
[Power storage control unit 120]
FIG. 8 is a diagram schematically illustrating a configuration example of the power storage control unit 120 in the power storage system 100 according to the fourth embodiment of the present disclosure. The power storage system 100 in the present embodiment is different from the power storage system 100 shown in FIG. 6 in that each power storage control unit 120 shares charge information, and other points are basically the same.

  As long as the charging information is information indicating a charging state, any information is within the range of the charging information in the present disclosure. The charging information may be a voltage of the battery unit 110 or the like. Each power storage control unit 120 may be configured to share charging information through communication. In that case, each power storage control unit 120 may acquire charging information from the corresponding monitoring unit 112 and transmit the acquired charging information to each other. Such sharing of charging information can also be realized by the configuration example of FIG. This will be specifically described below.

  As illustrated in FIG. 8, the power storage control unit 120 includes a charging information sharing unit 121 and a charging current value adjustment unit 122. The charging information sharing unit 121 includes a communication unit 121a and a charging information acquisition unit 121b. The charging current value adjustment unit 122 includes a determination unit 122a, a charging current value calculation unit 122b, and a charging current value setting unit 122c.

  The charging information sharing unit 121 acquires charging information (hereinafter referred to as its own charging information) from the monitoring unit 112 corresponding to the charging information sharing unit 121 by the charging information acquisition unit 121b. At this time, the own charging information may be acquired by communication via the signal line 105. The charging information sharing unit 121 transmits its own charging information to the power storage control unit 120 of the other party, that is, the sharing partner through the communication unit 121a. In addition, charging information sharing unit 121 receives the charging information of the other party transmitted from power storage control unit 120 of the other party through communication unit 121a. The communication unit 121a may be configured to transmit and receive charging information by wired communication or wireless communication. The charging information sharing unit 121 acquires the charging information received by the communication unit 121a by the charging information acquisition unit 121b. In this way, charging information for each battery unit 110 may be shared.

  The charging current value adjustment unit 122 determines whether or not the charging state of each battery unit 110 indicated by the shared charging information is a charging state in which the charging current value should be decreased by the determination unit 122a. Examples of the state of charge in which the charging current value should be decreased include that any one of the battery units 110 has reached a specific voltage value. The determination unit 122a may also determine whether or not the state of charge of each battery unit 110 is a state of charge that should increase the charge current value.

  When the determination unit 122a determines that the charging state of each battery unit 110 is a charging state in which the charging current value should be decreased, the charging current value adjustment unit 122 is charged by the charging current value calculation unit 122b. The charge current value to be set to is calculated. The charging current value calculation unit 122b may calculate the charging current value according to a preset algorithm. The charging current value calculation unit 122b may calculate the charging current value even when the determination unit 122a determines that the charging current value should be increased.

  The charging current value adjustment unit 122 sets the charging current value calculated by the charging current value calculation unit 122b in the charger 102 by the charging current value setting unit 122c. Thereby, the charging current value adjustment unit 122 decreases the charging current value of the charger 102. The operation mode of the charging current value adjustment unit 122 may include maintaining and increasing the charging current value.

  The charging information sharing unit 121 and the charging current value adjusting unit 122 can be realized by hardware, software, or both. The charging information sharing unit 121 and the charging current value adjusting unit 122 may be embodied by being installed as new software in an existing power storage control unit. This eliminates the need to add new hardware, thereby reducing costs.

[System operation example]
FIG. 9 is a flowchart illustrating an operation example of the power storage system 100 of the present embodiment. The operation example illustrated in FIG. 9 includes an embodiment of the power storage control method according to the present disclosure. A unique step in the operation example of the present embodiment is step 41 (S41) in FIG. 9 executed between step 11 (S11) and step 12 (S12).

  In step 41 (S41), the power storage control unit 120 shares the charging information. Details of this step 41 (S41) are illustrated in FIG.

  In step 41 (S41), first, in step 411 (S411) of FIG.

  Next, in step 412 (S412), the own charging information acquired in step 411 (S411) is transmitted to the other power storage control unit 120.

  Next, in step 413 (S413), the other party's charging information is received.

  Next, in step 414 (S414), the charging information of the other party received in step 413 (S413) is acquired, and the process proceeds to step 12 (S12).

  According to the present embodiment, the same effects as the power storage system 100 of FIG. 6 can be obtained, and the charging current value can be easily and appropriately adjusted based on the charging information of each battery unit 110. Overcurrent can be prevented more reliably.

<7. First Modification of Fourth Embodiment>
FIG. 11 is an overall view schematically showing the configuration of the power storage system 100 of the first modification example of the present embodiment. The power storage system 100 according to this modification includes a communication line 103. Other configurations and operations are basically the same as those of the power storage system 100 of FIG.

  As shown in FIG. 11, the power storage control units 120 are connected to each other by a communication line 103. Each power storage control unit 120 can communicate with each other via the communication line 103. The aspect of the communication line 103 is not limited. For example, the communication line 103 may be a communication line for bidirectional communication. The communication line for bidirectional communication may be a bus such as a serial bus or a parallel bus. The serial bus may be a CAN (Controller Area Network) bus or the like. By adopting the CAN bus, data communication between the respective power storage control units 120 can be stabilized.

  As illustrated in FIG. 11, the power storage system 100 may include a diode 106. In the example of FIG. 11, two or more diodes 106 are provided corresponding to each charger 102. The anode of the diode 106 is connected to the charger 102 corresponding to the diode 106. The cathode of the diode 106 is connected to the battery unit 110 corresponding to the diode 106. For example, the diode 106 prevents reverse current from flowing into the charger 102 from the battery unit 110 side.

  A load device 107 is connected in parallel to the power storage system 100 via the power line 104. Electric power is supplied from the battery units 110 to the load device 107 during discharging.

  According to the present modification, the same operation and effect as the power storage system 100 of FIG. 8 can be obtained, and charging information is shared between the two or more power storage control units 120 via the communication line 103 at a low cost. Therefore, overcurrent can be prevented at a low cost.

<8. Second Modification of Fourth Embodiment>
FIG. 12 is an overall view schematically showing the configuration of the power storage system 100 of the second modification example of the present embodiment. The power storage system 100 of this modification is different from the power storage system 100 of FIG. 11 in that each battery unit 110 includes a plurality of cells 111. Other configurations and operations are basically the same as those of the power storage system 100 of FIG.

  According to the power storage system 100 of the present modification, the same operational effects as the power storage system 100 of FIG. 11 can be obtained, and the output of the power storage system 100 can be increased. Furthermore, even if the battery unit 110 includes a plurality of cells 111 and thus the state of charge among the battery units 110 is likely to vary, overcurrent can be effectively prevented.

<9. Third Modification of Fourth Embodiment>
FIG. 13 is an overall view schematically showing a configuration of a power storage system 100 according to a third modification of the present embodiment. In the power storage system 100 of this modification, the battery unit 110 and the charger 102, the power storage control unit 120, and the diode 106 corresponding to the battery unit 110 are housed in a common housing body to constitute one power storage unit 101. This is different from the power storage system 100 of FIG. FIG. 13 representatively shows only one power storage unit 101. Other configurations and operations are basically the same as those of the power storage system 100 of FIG.

  In this modification, a portion 104 a used for parallel connection in the power line 104 may be detachable from the power storage unit 101 via a terminal portion 101 a that is electrically connected to the battery unit 110. The communication line 103 may also be attachable to and detachable from the power storage unit 101 via the terminal portion 101 b that is electrically connected to the power storage control unit 120. The aspect of the terminal portions 101a and 101b, for example, the position, the number, the structure, etc. are not limited.

  According to this modification, the same operation and effect as the power storage system 100 of FIG. 11 can be obtained, and the output of the power storage system 100 can be easily increased by adding the power storage unit 101.

<10. Fifth Embodiment>
[Power storage control unit 120]
The power storage system 100 of the present embodiment is different from the fourth embodiment in that the power storage control unit 120 adjusts the charging current value according to the number of battery units 110 having a voltage equal to or higher than a specific voltage value. Other configurations and operations are basically the same as those in the fourth embodiment.

  Here, “adjusting the charging current value according to the number of battery units 110 having a voltage equal to or higher than the specific voltage value” may include reducing the charging current value as the number increases. As an example of such adjustment, the power storage control unit 120 reduces the charging current value as the number of battery units 110 having a voltage equal to or higher than a specific voltage value is less than a predetermined number. Also good. In this case, the power storage control unit 120 may not change the charging current value regardless of the number of battery units 110 having a voltage equal to or higher than the specific voltage value. As another example, the power storage control unit 120 is configured such that the battery unit 110 having a voltage equal to or higher than a specific voltage value is detected under a condition that a voltage drop of the battery unit 110 being charged is not detected due to discharge to the load device 107 or the like. The charging current value may be decreased as the number increases. In this case, the power storage control unit 120 maintains or maintains the charging current value regardless of the number of battery units 110 having a voltage equal to or higher than the specific voltage value under the condition that the voltage drop of the battery unit 110 being charged is detected. It may be increased.

  Here, “reducing the charging current value as the number of battery units 110 having a voltage equal to or higher than a specific voltage value increases” means that the charging current value is decreased stepwise as the number increases. Also good. As an example of such adjustment, for example, the power storage control unit 120 determines that the charging current value increases as the number of battery units 110 having a voltage equal to or higher than a specific voltage value is less than a predetermined number. May be decreased step by step. In this case, the power storage control unit 120 may not change the charging current value regardless of the number of battery units 110 having a voltage equal to or higher than the specific voltage value. As another example, the power storage control unit 120 may charge current with an increase in the number of battery units 110 having a voltage equal to or higher than a specific voltage value under the condition that a voltage drop of the battery unit 110 being charged is not detected. The value may be decreased step by step. In this case, the power storage control unit 120 maintains or maintains the charging current value regardless of the number of battery units 110 having a voltage equal to or higher than the specific voltage value under the condition that the voltage drop of the battery unit 110 being charged is detected. It may be increased.

[System operation example]
The power storage control unit 120 may control the charging current value to be supplied to the charger 102 according to the following expressions (1) and (2).
Iin = (Ic / N) × (N−M) (where M <N) (1)
Iin = Ic / N (M = N) (2)
In the expressions (1) and (2), Iin is a charging current value. Ic is a constant current value in constant current charging. N is the number of battery units 110 for which charging is detected. When all battery units 110 are charged, N is equal to the number of battery units 110 connected in parallel. M is the number of battery units 110 having a voltage equal to or higher than a specific voltage value.

[Time chart]
An example of the control of the charging current value by the power storage control unit 120 according to the equations (1) and (2) is shown in the time chart of FIG.

  FIG. 14 shows a time chart for three battery units 110 when N = 3. Hereinafter, the battery unit 110 corresponding to the time chart of FIG. 14A is defined as the first battery unit 110, and the charger 102 corresponding to the first battery unit 110 is defined as the first charger 102. Moreover, the battery unit 110 corresponding to the time chart of FIG. 14B is defined as the 2nd battery unit 110, and the charger 102 corresponding to the 2nd battery unit 110 is defined as the 2nd charger 102. Furthermore, the battery unit 110 corresponding to the time chart of FIG. 14C is defined as the third battery unit 110, and the charger 102 corresponding to the third battery unit 110 is defined as the third charger 102.

  The horizontal axis in FIG. 14 indicates time (t). The vertical axis | shaft of FIG. 14 shows the charging current value (I1-I3) which flows into each battery unit 110, and the voltage (V1-V3) of each battery unit 110. In FIG.

  Here, as shown in FIG. 14, after the start of charging the first to third battery units 110, M = 0 until the time T1 when the battery unit 110 having a specific voltage value (SV) is first detected. Therefore, Iin = Ic is set from the equation (1). Thus, during the period from the start of charging to time T1, a constant current value Ic is supplied by each charger 102, and constant current charging is performed. In the example of FIG. 14, the first battery unit 110 (FIG. 14A) is first detected as the battery unit 110 having a specific voltage value.

  Next, at time T1, when the first battery unit 110 reaches a specific voltage value, it increases to M = 1. Thereby, Iin = (2/3) Ic is set according to the equation (1). For this reason, after time T1, (2/3) Ic is supplied by each charger 102 until a new phase of decreasing the charging current value is reached.

  Thereafter, at time T2, the first battery unit 110 reaches the upper limit voltage value (ULV). Thereby, the first battery unit 110 is disconnected from the first charger 102 by the switch control of the switch control unit 113, and the charging current does not flow. The charging current (2/3) Ic of the first charger 102 that has lost its place due to this interruption flows into the second and third battery units 110. At this time, if the ease of cross current flow into the electric circuit, such as impedance and internal resistance, is equal between the electric circuits of the second and third battery units 110, the cross current (2/3) Ic from the first charger 102 is obtained. Is diverted to the second and third battery units 110 by (1/3) Ic. However, such a mode of diversion is merely an example, and does not limit the scope of the present disclosure.

  Due to the cross current from the first charger 102, the charging current flowing through the second and third battery units 110 increases. However, since the charging current value of the first to third chargers 102 has been reduced to (2/3) Ic in advance, the charging current flowing through the second and third battery units 110 is (1/3) Even if the cross currents of Ic are added, it becomes Ic. Therefore, a current exceeding Ic, that is, an overcurrent does not flow through the second and third battery units 110 due to the cross current from the first charger 102.

  Thereafter, at time T3, the second battery unit 110 (FIG. 14B) reaches the specific voltage value, and the first battery unit 110 is at the upper limit voltage value, so that it increases to M = 2. Thereby, Iin = (1/3) Ic is set according to the equation (1). For this reason, (1/3) Ic is supplied by each charger 102 after time T3. At this time, since the cross current (1/3) Ic from the first charger 102 is equally assigned by (1/6) Ic, the charging current values flowing in the second and third battery units 110 are (1 / 2) Every Ic.

  Thereafter, at time T4, the second battery unit 110 reaches the upper limit voltage value. As a result, the second battery unit 110 is disconnected from the second charger 102 and no charging current flows. The charging current of the second charger 102 that has lost its place due to this interruption flows into the third battery unit 110. At this time, the charging current of the first charger 102 also flows into the third battery unit 110.

  Due to the cross current from the first and second chargers 102, the charging current flowing through the third battery unit 110 increases. However, since the charging current value of the first to third chargers 102 has been reduced to (1/3) Ic in advance, the charging current flowing through the third battery unit 110 is (1/3) Ic. Even if the cross current component is included, Ic is obtained. Therefore, the overcurrent exceeding Ic does not flow through the third battery unit 110 due to the cross current from the first and second chargers 102.

  Thereafter, at time T5, the third battery unit 110 (FIG. 14C) reaches the specific voltage value, and the first and second battery units 110 are at the upper limit voltage value, so that M = 3. To increase. At this time, since M = N, Iin = (1/3) Ic is set not by the equation (1) but by the equation (2). Thereby, after time T5, (1/3) Ic is continuously set or maintained in each charger 102, and Ic is supplied to the third battery unit 110 until the end of charging even after the specific voltage value is exceeded. The

  The control of the charging current value shown in FIG. 14 is one form of adjustment of the charging current value according to the number of battery units 110 having a voltage equal to or higher than the specific voltage value. Specifically, the control of the charging current value shown in FIG. 14 is one form of adjustment including decreasing the charging current value as the number of battery units 110 having a voltage equal to or higher than a specific voltage value increases. More specifically, the control of the charging current value shown in FIG. 14 includes an adjustment including a stepwise decrease in the charging current value as the number of battery units 110 having a voltage equal to or higher than the specific voltage value increases. It is one form.

[flowchart]
Next, an example of the operation of the entire system is shown in the flowchart of FIG. The operation example of FIG. 15 is different from FIG. 9 in that steps 51 (S51) to 55 (S55) are executed between step 12 (S12) and step 22 (S22).

  In step 51 (S51), the power storage control unit 120 determines whether or not M in the expressions (1) and (2) has increased. If a positive determination result is obtained in step 51 (S51), the process proceeds to step 52 (S52), and if a negative determination result is obtained, the process proceeds to step 15 (S15).

  In step 52 (S52), the power storage control unit 120 determines whether or not the magnitude relationship between M and N described in the equations (1) and (2) is M <N. When a positive determination result is obtained in step 52 (S52), the process proceeds to step 53 (S53), and when a negative determination result, that is, M = N is obtained, step 54 (S54). )

  In step 53 (S53), the power storage control unit 120 calculates the charging current value by substituting M and N into the equation (1), and proceeds to step 55 (S55).

  In step 54 (S54), the power storage control unit 120 calculates the charging current value by substituting M and N into the equation (2), and proceeds to step 55 (S55).

  In step 55 (S55), the power storage control unit 120 sets the charging current value calculated in step 53 (S53) or step 54 (S54) in the charger 102, and proceeds to step 22 (S22).

  In addition to the above, in the operation example of FIG. 15, step 56 (S56) is executed after step 23 (S23). In step 56 (S56), the power storage control unit 120 determines whether a condition for ending the control of the charger 102 is satisfied. In other words, in step 56 (S56), it is determined whether or not an event for ending the control of the charger 102 has been detected. The condition, that is, the event in this step may be, for example, that the battery unit 110 being charged is no longer detected. If a positive determination result is obtained in step 56 (S56), the process is terminated, and if a negative determination result is obtained, the process returns to step 41 (S41).

  According to the power storage system 100 of the present embodiment, the same operational effects as in the fourth embodiment can be obtained, and the adjustment of the charging current value according to the number M of causes of overcurrent can be optimized. it can. Furthermore, according to the present embodiment, the charging current value can be decreased stepwise in accordance with the sequential increase of the cause of occurrence of overcurrent, so that it is possible to flexibly cope with changes in the charging state.

<11. Modification of Fifth Embodiment>
In the time chart of FIG. 14, M increases by 1 and charging of each battery unit 110 is completed one by one. Formula (1) can deal with not only such sequential charging end but also simultaneous charging end.

  For example, as shown in FIG. 16, it is assumed that the first battery unit 110 and the second battery unit 110 simultaneously reach a specific voltage value (SV) at time T1. In this case, since M = 2 at that time, the charging current value can be set to (1/3) Ic from Equation (1).

  On the other hand, FIG. 17 is a time chart when the charging current value is not decreased according to the state of charge as in the present disclosure. As shown in FIG. 17, in the case where the charging current value of the charger is not decreased, every time the battery unit is disconnected from the charger, the cross current from the charger causes the charging current flowing to the other battery units to be a constant current. Push up above the value to generate overcurrent. The overcurrent becomes more prominent as the number of battery units cut off from the charger increases.

  In the example of FIGS. 14 and 16, when the number of battery units 110 having a specific voltage value or more increases, the charging current values of the chargers 102 are set to be equal to each other. However, the present disclosure is not limited to this. For example, when the constant current values in the constant current charging of each charger 102 are different from each other, or when the ease of cross current flow into each battery unit 110 is different, the setting of the charging current value of each charger 102 is mutually different. It may be different.

  The above embodiments and modifications may be combined as appropriate.

  The operational effects described in the embodiments and the modifications are merely examples and are not limited, and other operational effects may be provided. This indication should just show any one of a plurality of operation effects indicated in each embodiment and a modification.

In addition, the present disclosure can take the following configurations.
(1) one or two or more cells and two or more battery units connected to each other in parallel with a monitoring device for monitoring the state of charge;
One or more chargers for supplying a charging current to each battery unit;
One or two or more power storage control devices that control a charging current value supplied to each battery unit,
The power storage control device is a power storage system configured to reduce the charging current value according to a charging state of each battery unit.
(2) The battery unit includes a shut-off device that cuts off the connection with the charger when the voltage reaches an upper limit voltage value,
The power storage system according to (1), wherein the power storage control device is configured to decrease the charging current value when a voltage of the battery unit becomes a specific voltage value smaller than the upper limit voltage value.
(3) The power storage control device causes the charger to supply a constant current value until the battery unit having the specific voltage value is first detected, and the battery unit having the specific voltage value is first After the detection, the power storage system according to (2), wherein the current value supplied to the charger is adjusted so that the charging current value supplied to each battery unit is equal to or less than the predetermined current value.
(4) The power storage system according to any one of (1) to (3), including two or more power storage control devices, wherein the charging information is shared between the two or more power storage control devices.
(5) The power storage system according to (4), configured to share the charging information by communication, (6) including a communication line that interconnects the two or more power storage control devices,
The power storage system according to (5), wherein the two or more power storage control devices transmit and receive the charging information to and from each other via the communication line.
(7) The first power storage control device in the two or more power storage control devices acquires the charging information from the monitoring device corresponding to the first power storage control device, and uses the charging information as the two or more power storage control devices. The power storage system according to (5) or (6), which is configured to transmit to a second power storage control device in the device.
(8) The power storage system according to (2) or (3), wherein the power storage control device adjusts the charging current value according to the number of the battery units having a voltage equal to or higher than the specific voltage value.
(9) The power storage system according to (8), wherein the power storage control device performs the adjustment including reducing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases.
(10) The power storage control device is configured to perform the adjustment including gradually decreasing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases. (9) The electricity storage system described.
(11) A power storage control method for reducing a charging current value supplied to the battery unit according to a charging state of two or more battery units including one or more cells and connected in parallel to each other.
(12) The battery unit is disconnected from the charger when the voltage reaches an upper limit voltage value,
The power storage control method according to (11), wherein the charging current value is decreased when the voltage of the battery unit becomes a specific voltage value smaller than the upper limit voltage value.
(13) Until the battery unit having the specific voltage value is first detected, the charger is supplied with a constant current value, and after the battery unit having the specific voltage value is first detected, The power storage control method according to (12), wherein a current value supplied to the charger is adjusted so that a charging current value supplied to each battery unit is equal to or less than the constant current value.
(14) The power storage control method according to (12) or (13), wherein the charging current value is adjusted according to the number of the battery units having a voltage equal to or higher than the specific voltage value.
(15) The power storage control method according to (14), wherein the adjustment including reducing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value is increased.
(16) The power storage control method according to (15), wherein the adjustment including the stepwise reduction of the charging current value with an increase in the number of battery units having a voltage equal to or higher than the specific voltage value is performed.
(17) causing the computer to function as means for reducing a charging current value supplied to two or more battery units including one or two or more cells connected in parallel to each other according to a charging state of each battery unit; Power storage control program.
(18) a battery unit including one or more cells and a monitoring device for monitoring a charge state;
A charger for supplying a charging current to the battery unit;
A power storage control device for controlling a charging current value supplied to the battery unit,
The power storage control device is configured to reduce the charging current value according to a charging state of the battery unit and a charging state of a battery unit connected in parallel to the battery unit.

DESCRIPTION OF SYMBOLS 100 Power storage system 102 Charger 110 Battery unit 111 Cell 112 Monitoring part 120 Power storage control part

Claims (15)

Two or more battery units provided with one or more cells and a monitoring device for monitoring the state of charge and connected in parallel to each other;
One or more chargers for supplying a charging current to each battery unit;
One or two or more power storage control devices that control a charging current value supplied to each battery unit,
The power storage control device is a power storage system configured to reduce the charging current value according to a charging state of each battery unit. The battery unit includes a shut-off device that shuts off the connection with the charger when the voltage reaches an upper limit voltage value,
The power storage system according to claim 1, wherein the power storage control device is configured to decrease the charging current value when a voltage of the battery unit becomes a specific voltage value smaller than the upper limit voltage value.   The power storage control device supplies a constant current value to the charger until the battery unit having the specific voltage value is first detected, and the battery unit having the specific voltage value is first detected. 3. Thereafter, the power storage system according to claim 2, wherein the current value supplied to the charger is adjusted so that the charge current value supplied to each battery unit is equal to or less than the constant current value.   The power storage system according to claim 2, comprising two or more power storage control devices and configured to share charging information between the two or more power storage control devices. A communication line connecting the two or more power storage control devices to each other;
The power storage system according to claim 4, wherein the two or more power storage control devices are configured to mutually transmit and receive the charging information via the communication line.   The first power storage control device in the two or more power storage control devices acquires the charging information from the monitoring device corresponding to the first power storage control device, and uses the charging information in the second power storage control device. The power storage system according to claim 4, wherein the power storage system is configured to transmit to the second power storage control device.   The power storage system according to claim 2, wherein the power storage control device is configured to adjust the charging current value according to the number of the battery units having a voltage equal to or higher than the specific voltage value.   The power storage system according to claim 7, wherein the power storage control device is configured to perform the adjustment including reducing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases.   The power storage device according to claim 8, wherein the power storage control device is configured to perform the adjustment including gradually decreasing the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases. system.   A power storage control device configured to reduce a charging current value supplied to two or more battery units including one or more cells and connected in parallel to each other in accordance with a charging state of each battery unit.   The power storage control device according to claim 10, wherein the charge current value is decreased when the voltage of the battery unit reaches a specific voltage value.   The power storage control device according to claim 11, wherein the charging current value is adjusted according to the number of the battery units having a voltage equal to or higher than the specific voltage value.   The power storage control device according to claim 12, wherein the adjustment is performed such that the charging current value is decreased as the number of battery units having a voltage equal to or higher than the specific voltage value is increased.   14. The power storage control device according to claim 13, wherein the adjustment includes a stepwise decrease in the charging current value as the number of battery units having a voltage equal to or higher than the specific voltage value increases. A power storage control method for reducing a charging current value supplied to a battery unit according to a charging state of two or more battery units including one or two or more cells connected in parallel to each other.

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